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Bill and Brian are watching intense inflow into the storm and in fact, one chaser reported damaging inflow with power poles down and roof damage ahead of the lead supercell. But there is no substantial circulation at low-levels. The storm has an appearance of a big HP blob with occluding low-level mesos quickly surrounded by heavy rain, hail and probably cold air. However, they feel that it still deserves a 40% probability.
Jim LaDue (EWP Weekly Coordinator, 5-9 May)
Hail:
0035UTC: MESH is only showing 1.75″ in the lead storm. The trailing storm is coming up. The lead storm recently came in with softball report according to SHAVE. Cynthia and Craig went with 90% for the lead and 80% for the trailing storm.
Jim LaDue (EWP Weekly Coordinator, 5-9 May)
New updraft is going up after the last occlusion.
Bill and Brian are considering going higher TOR probs with a new update. They centered the ellispse in the notch and are going with storm motion 290 23, Cynthia’s going 295 20. TOR probabilities are going higher – 80% dropping to 70% in 20 min.
Jim LaDue (EWP Weekly Coordinator, 5-9 May)
Hail threat:
Cynthia’s turning off that irritating ellipse and going with a multi-vertex polygon because the shape of the hail threat according to MESH is not an ellipse anymore. There’s still some issues with building the correctly shaped threat polygon.
The storm wrapped up again and the updraft intensity’s come down a bit. However the trailing storm is now merging with the lead supercell through the initiation of intervening cells. Does Cindy and Craig combine the two storms into one threat area? They’ll keep them separate for now.
Jim LaDue (EWP Weekly Coordinator, 5-9 May)
Brian and Bill are to issue TOR probabilities. They’re going with Initial probabilities of 50% but they think it’ll recycle so they want the probabilities to go down and then go up. To play it conservative they’ll go down to 40% in 20 min. They’d go with a legacy TOR but they aren’t going higher because the initial TVS is totally rain wrapped and has come down in velocity difference. There’s no report either.
Jim LaDue (EWP Weekly Coordinator, 5-9 May)
The supercell is recycling as MESH values rose and the reflectivity is rising as well as the velocity couplet.
The initial storm motion was a little fast so Cindy and Brian lowered it down to 20 kts. They’ll be keeping the hail prob of 100% initial and 90% in 30 min. Their storm motion uncertainty is 15deg and 10kts. They went with ellipses because the initial hail signature was circular. They’ll have to issue a new threat ID if the storm changed shapes.
So far the team has not been issuing TOR prob guidance. Greg’s starting up a new machine for TOR prob warnings.
Jim LaDue (EWP Weekly Coordinator, 5-9 May)
Cindy is in the driver’s seat for probwarn while Craig, Bill and Brian are contributors. The southeastern supercell underwent a major occlusion with an incredibly aggressive, hail-filled RFD and now the storm cycled down a little. However 100% hail probability is gauranteed and ended with 70% at 30 min. The storm following behind was warned for a 70% hail and kept it that high.
The low-level reflectivity and even the MESH show a hole in the middle of the storm as a result of the core in the RFD wrapping all the way around until it met the forward flank core. New convection exploded on the leading edge of the RFD.
Jim LaDue (EWP Weekly Coordinator, 5-9 May)
Two areas of concern grabs our attention today. One area is associated with the departing system toward the east coast where a slight risk has been laid out from AL to VA. Storms were already occurring in AL with several TORs at briefing time, however the threat may focus more in the Carolinas and VA by the time any prob warn activities commenced. The second area is a slight risk area in KS and northern OK. This area already has convection forming in eastern CO. The moisture’s a little light but lapse rates are much steeper than the eastern risk zone. Both areas have sufficient shear for supercells.
The shortwave trough in CO is progged to move well to the north of the PAR and CASA areas and the probability of convection is small. The most likely time for convection in these areas would be after 0300 UTC.
We will probably go with probability warning activities following the SHAVE experiment.
At 2200 UTC, SHAVE was already active on two large hail producing supercells in western KS. Probwarn activities are focusing on the DDC area again.
Jim LaDue (EWP Weekly Coordinator, 5-9 May)
Since some of the damage from last night was across the street from my kids’ school, I set off from there this morning with only a Nokia N95 as assistance. For those who don’t know, this cameraphone is pretty nice:
I basically drove around and took pictures with the phone and then uploaded them. It seemed great! Only, when I got back to NSSL, I discovered that it didn’t really go so well:
The practical upshot is that the GPS Logger / regular digital camera survey method will still work better, unless you want to auto-upload your results to a web site.
(Travis Smith)
A quick look at the PAR data indicates two separate short-lived circulations that passed through Oklahoma County and were scanned by the PAR.
Survey photos KML from Piedmont to Meridian and NW Expressway are attached. There was an almost continuous narrow path between the two locations, though part of it would have been over Lake Overholser.
Too bad there is no EF-scale DOD for movable metal bleachers. I saw loads of those tossed around. One of them badly bent a steel-braced awning at the baseball fields.
A photo from newsok.com was in the back yard of someone’s house in Yukon, so I didn’t get in to see the damage myself. The only other stuff I saw in that area were some stockade fences blown down and some limbs removed (no uprooted trees or anything). So that part of the path could be EF1 based on the picture, but EF0 based on everything else.
Kiel and Angelyn surveyed the Edmond / NOKC circulation. Kiel writes:
I’ll use tornado lightly here…radar really helped pick this guy out. Anyways, attached is Angelyn’s and my survey. Gonna go EF0 on this bad boy…sporadic damage that eventually lined up into a path (2.8 miles long by 20 yards wide).
DI/DODs:
Trees (hard/softwood): DOD 3
Single family home: DOD 2
Aparment building: DOD 2Given the last DI/DOD, winds up to 82 MPH.
(Travis Smith)
